Insulated electrical wire usually comprises a conductive core and a sheath of insulating material. The bare ends of wires are insulated in the appliance to which they are attached, or by a separate insulator. Separate insulators can be expensive.
In manufacture of a wiring harness it may be necessary to join several wires. This may be accomplished by using connector devices but a more reliable connection can be made by joining the conductive cores by soldering or welding, and applying an insulating boot. In conditions where moisture or corrosion is likely it is important that the boot is sealed.
Bared ends of insulated wires may be capped by a boot containing fluid substance which is solidified after the boot is fitted. Such an arrangement is disclosed for example in U.S. Pat. No. 3,550,765, and encapsulates the bare wire ends.
However this kind of boot may be unreliable in wet or corrosive conditions if the insulated wires lie against the wall of the boot, thus preventing the fluid substance encircling the wires. U.S. Pat. No. 3,597,528 discloses a cover to centralize wires in the boot, but this additional component increases cost and assembly time.
Problems may also arise with this kind of boot if the bare wire is not sufficiently inserted in the fluid substance, thus leading to insufficient depth of insulation. Further problems arise if the depth of insertion in the boot is correct but the amount of fluid substance is insufficient, or if external pressure results in insufficient encapsulation of the bared wire end.